The histones are now a very well established part of Biochemistry. The interpretation of all that is known about them, however, is already too great a burden for a single author to undertake. Indeed, a survey of the indexed literature shows that the number of publications on the histones has approximately doubled in every three years for the past 15 years, and is now several hundred a year. It is time then to bring together in one publication the major topics embraced by this great research effort. This book therefore endeavours to give, in six chapters, a broad and searching account of the biochemistry and biophysics of these interesting proteins and their complexes with nucleic acids, the nucleohistones. Each chapter is written by different authors who are all active in this research and who have had many years experience with these proteins and their complexes. Chapters 1, 2, part of 3, and all of Chapters 5 and 6, cover the occurrence, preparation, characterization, sequence structure, bio­ physical properties and finally, the biosynthesis and functions of the histones. The other part of Chapter 3, the whole of Chapter 4 and to a less extent some other chapters, all discuss the properties and structure of the nucleohistones. The study of these complexes is undoubtedly of great importance in bridging the gaps in our knowledge of template activity and differentiation as well as of chromosomal structure and mechanics.